To generate fine bubbles of diameter of a nanometer order below a micron, conventionally, a turning stream is generated in a gas and liquid mixing fluid, and the gas contained in the liquid is subdivided with a shear force produced in the liquid. For example, an equipment is known which supplies a gas and liquid mixing fluid into a cylinder from an inner circumference tangential direction with a vortex pump and then miniaturizes bubbles during revolutions within the cylinder (for example, refer to Japanese patent No. 4118939).
Moreover, a phenomenon is known that if a liquid is supplied to a surface, of a substrate consisting of the piezoelectric material etc., on which a surface acoustic wave is propagating, the liquid receives an energy of the surface acoustic wave, flows or vibrates, and flies as fine particles. Generators which atomize a liquid by using this phenomenon are proposed variously, and a method is known which atomizes a liquid drop by breathing out the drop from an ink jet unit and supplying the drop onto a surface where a surface acoustic wave is propagating (for example, refer to Japanese Laid-open Patent Publication Hei 11-114467).
However, a pump for highly pressurizing a liquid, and so on, are necessary in the generating method of the fine bubbles shown in the Japanese patent No. 4118939 mentioned above, and the miniaturization of apparatus is difficult. Moreover, in the generating method of mist shown in the Japanese Laid-open Patent Publication Hei 11-114467, it is necessary to stably supply the drop to be atomized with sufficient accuracy, and a constitution becomes complicated. Moreover, such a method or a generator is not known which can miniaturize the equipment and can simultaneously generate both of mist and fine-bubble of nanometer order or can generate only desired one.